/Multiple Granemfsefon. 121 



the galvanic battery was discovered before it 

 became a useful servant of man. It was fifty 

 years or more after the discovery by Faraday 

 of magneto-electricity before it found a use- 

 ful application beyond that of a mere toy, but 

 now it is one of the most useful servants we 

 have, as shown in its wonderful development 

 in electric lighting and electric railroads, to 

 say nothing of its heating qualities and the 

 useful purpose it serves in driving machinery. 

 The interesting discoveries of Professor 

 Crookes in p'assing a current of electricity 

 through tubes of high vacua waited many 

 years before they found a practical use in the 

 X-ray, that promises to be of great service in 

 medicine and surgery. 



The transmission of musical harmonies 

 telegraphically, while in itself of great scien- 

 tific interest, was of no practical use, but it 

 led to other inventions, of which it is the base, 

 that are transcendently useful in every-day 

 life. The transmission of harmonic sounds 

 by. electricity underlies the principle of the 

 telephone. There is a vast difference, in prin- 

 ciple, between the transmission of simple 

 melody, which is a combination of musical 

 tones transmitted successively one tone fol- 

 lowing another- and tin- Inm-mission of har- 

 mony, which inv..lv- the Iran-minion of two 

 or UK. re tows siniult;uicou>ly. The former 

 can be transmitted by a make-and-break cur- 



